Printing system having staggered hammer release

Abstract

In an impact printer system in which various hammer springs mounted in side-by-side relation along a reciprocating hammer bank are selectively released to cause an impact tip mounted at the upper end of the hammer spring to impact a paper or other printable medium, the hammer springs are divided into two different groups and the release of the hammer springs in the different groups is staggered. Alternate ones of the hammer springs comprise a first group of hammer springs which are selectively released at the beginning of each of a succession of cycles as the hammer bank sweeps across the printable medium. The remaining ones of the hammer springs comprise a second group and are releaseable at a midway point through each cycle. When any given hammer spring is released, an electro-mechanical mutual inductance effect is released in which the adjacent hammer springs and associated pole pins provide a beneficial improvement in the mutual inductance, and the current required to release each hammer spring and the total power required to operate the hammer bank are significantly reduced. To compensate for the staggered release of the hammer springs, the hammer springs are located to provide other than uniform spacing between the impact tips. The impact tip on each hammer is spaced a first fixed distance from the impact tip on the adjacent hammer on one side thereof and a second fixed distance from an impact tip on an adjacent hammer on the other side thereof. The difference between the first and second fixed distances is equal to the distance that the hammer bank travels relative to the printable medium during each of the succession of cycles.